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SELECT 
  state_descriptions.state 
FROM 
  states 
  LEFT JOIN state_descriptions ON state_descriptions.state_id = states.state_id 
  AND state_descriptions.lang_code = 'en' 
WHERE 
  states.country_code = 'US' 
  AND states.code = ''

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}